/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.linkis.engineconnplugin.flink.client.sql.operation.impl;

import org.apache.linkis.engineconnplugin.flink.client.context.ExecutionContext;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.NonJobOperation;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.result.ColumnInfo;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.result.ConstantNames;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.result.ResultKind;
import org.apache.linkis.engineconnplugin.flink.client.sql.operation.result.ResultSet;
import org.apache.linkis.engineconnplugin.flink.context.FlinkEngineConnContext;
import org.apache.linkis.engineconnplugin.flink.exception.SqlExecutionException;

import org.apache.commons.lang3.StringUtils;
import org.apache.flink.table.api.DataTypes;
import org.apache.flink.table.api.TableColumn;
import org.apache.flink.table.api.TableEnvironment;
import org.apache.flink.table.api.TableSchema;
import org.apache.flink.table.api.WatermarkSpec;
import org.apache.flink.table.types.logical.BooleanType;
import org.apache.flink.table.types.logical.LogicalType;
import org.apache.flink.types.Row;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/** Operation for DESCRIBE TABLE command. */
public class DescribeTableOperation implements NonJobOperation {
    private final ExecutionContext context;
    private final String tableName;

    public DescribeTableOperation(FlinkEngineConnContext context, String tableName) {
        this.context = context.getExecutionContext();
        this.tableName = tableName;
    }

    @Override
    @SuppressWarnings("unchecked")
    public ResultSet execute() throws SqlExecutionException {
        // the implementation should be in sync with Flink, see FLINK-17112
        final TableEnvironment tableEnv = context.getTableEnvironment();
        TableSchema schema;
        try {
            schema = context.wrapClassLoader(() -> tableEnv.from(tableName).getSchema());
        } catch (Throwable t) {
            // catch everything such that the query does not crash the executor
            throw new SqlExecutionException("No table with this name could be found.", t);
        }

        Map<String, String> fieldToWatermark = new HashMap<>();
        for (WatermarkSpec spec : schema.getWatermarkSpecs()) {
            fieldToWatermark.put(spec.getRowtimeAttribute(), spec.getWatermarkExpr());
        }

        Map<String, String> fieldToPrimaryKey = new HashMap<>();
        if (schema.getPrimaryKey().isPresent()) {
            List<String> columns = schema.getPrimaryKey().get().getColumns();
            String primaryKey = "PRI(" + String.join(", ", columns) + ")";
            for (String column : columns) {
                fieldToPrimaryKey.put(column, primaryKey);
            }
        }

        List<TableColumn> columns = schema.getTableColumns();
        List<Row> data = new ArrayList<>();
        for (TableColumn column : columns) {
            LogicalType logicalType = column.getType().getLogicalType();

            String name = column.getName();
            String type = StringUtils.removeEnd(logicalType.toString(), " NOT NULL");
            boolean isNullable = logicalType.isNullable();
            String key = fieldToPrimaryKey.getOrDefault(column.getName(), null);
            String computedColumn = column.getName();
            String watermark = fieldToWatermark.getOrDefault(column.getName(), null);

            data.add(Row.of(name, type, isNullable, key, computedColumn, watermark));
        }

        return ResultSet.builder()
                .resultKind(ResultKind.SUCCESS_WITH_CONTENT)
                .columns(
                        ColumnInfo.create(
                                ConstantNames.DESCRIBE_NAME, DataTypes.STRING().getLogicalType()),
                        ColumnInfo.create(
                                ConstantNames.DESCRIBE_TYPE, DataTypes.STRING().getLogicalType()),
                        ColumnInfo.create(ConstantNames.DESCRIBE_NULL, new BooleanType()),
                        ColumnInfo.create(
                                ConstantNames.DESCRIBE_KEY, DataTypes.STRING().getLogicalType()),
                        ColumnInfo.create(
                                ConstantNames.DESCRIBE_COMPUTED_COLUMN,
                                DataTypes.STRING().getLogicalType()),
                        ColumnInfo.create(
                                ConstantNames.DESCRIBE_WATERMARK,
                                DataTypes.STRING().getLogicalType()))
                .data(data)
                .build();
    }
}
